Allochthonous terranes involved in the Variscan suture of NW Iberia: A review of their origin and tectonothermal evolution
| العنوان: | Allochthonous terranes involved in the Variscan suture of NW Iberia: A review of their origin and tectonothermal evolution |
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| المؤلفون: | Rubén Díez Fernández, Sonia Sánchez Martínez, José Manuel Fuenlabrada, Alicia López Carmona, Javier Fernández-Suárez, Pilar Andonaegui, Jacobo Abati, Ricardo Arenas, Richard Albert, Axel Gerdes, Pablo González Cuadra, Francisco J. Rubio Pascual |
| المساهمون: | Ministerio de Economía y Competitividad (España) |
| المصدر: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| بيانات النشر: | Elsevier BV, 2016. |
| سنة النشر: | 2016 |
| مصطلحات موضوعية: | Paleozoic paleogeography, 010504 meteorology & atmospheric sciences, Subduction, Allochthonous terranes, Continental crust, Ophiolites, Pangea, Mélange, 010502 geochemistry & geophysics, Ophiolite, Variscan suture, 01 natural sciences, Devonian, Nappe, Paleontology, High-P metamorphism, General Earth and Planetary Sciences, Suture (geology), Geology, 0105 earth and related environmental sciences, Terrane |
| الوصف: | NW Iberia includes a rather complete section of a Variscan suture, where different terranes with continental or oceanic affinities appear with clear structural relationships. Three groups of terranes, namely Upper, Ophiolitic and Basal units and a frontal tectonic mélange appear in Galicia, in Cabo Ortegal, Órdenes and Malpica-Tui complexes. They constitute a huge allochthonous pile thrust over the Iberian parautochthonous and autochthonous domains, which represent the section of the Gondwanan margin that escaped continental subduction during the Variscan cycle. Considering the allochthonous character of the nappe pile and the strong deformation associated to the Variscan collision, there are problems to identify the original tectonic setting of the terranes and thence, it is difficult to reconstruct the paleogeographic context during the Variscan and pre-Variscan times in detail. Key features to perform any model for the Variscan convergence should consider the existence of two different high-P metamorphic events (dated at c. 400 and 370 Ma, respectively), separated in time for the generation of mafic-ultramafic sequences at c. 395 Ma which constitute the most common ophiolites described in the Variscan suture. Some dynamic models developed in NW Iberia have important problems to explain the observed tectonothermal evolution, especially the older high-P metamorphic event and the exhumation of deeply subducted transitional-type sections. On the other hand, the recently discovered participation of an older continental crust in the generation of different protoliths of the Middle Devonian ophiolites, makes difficult the interpretation of these ophiolites in relation to open wide oceanic domains. This paper describes the distribution, structure, lithologies, geochronology and chemical composition of the terranes involved in the Variscan suture of NW Spain. The scope of this description ranges from detailed regional aspects to the discussion of the development of the Variscan Orogen in the context of the assembly of Pangea. A two-stage collisional model affecting a wide Gondwanan platform may explain most of the evidences in NW Iberia. The generation of a long pull-apart basin probably occurred after the first collision, where the Devonian ophiolites were formed. These ophiolites have been in general described in the context of the Rheic Ocean, but according to the new existing data they do not seem related to this ocean, but rather they were formed after its closure. Financial support has been provided by the Spanish project CGL2012-34618 (Ministerio de Economía y Competitividad). |
| تدمد: | 0012-8252 |
| DOI: | 10.1016/j.earscirev.2016.08.010 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::48e877ea9b5b2f7cfd81088b2ffd420e https://doi.org/10.1016/j.earscirev.2016.08.010 |
| Rights: | OPEN |
| رقم الانضمام: | edsair.doi.dedup.....48e877ea9b5b2f7cfd81088b2ffd420e |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 00128252 |
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| DOI: | 10.1016/j.earscirev.2016.08.010 |